A preliminary study of an alternative method for evaluating skin sensitizing potential of chemicals

Background: In order to comply with the European legislation concerning the risk assessment of skin sensitizers, considerable progress has been made in developing alternative methods, such as human cell line activation test (h-CLAT). H-CLAT is based on cytometric measurement of fluorescence emitted by anti-CD54 and anti-CD86 antibodies in THP-1 cells. Following this method, a range of substances have been analyzed; the emitted fluorescence, generally at low intensity, has caused problems concerning the interpretation of results. Aim: Find an alternative parameter to h-CLAT for evaluating the sensitizing potential of chemicals. Materials and Methods: Cells have been analyzed with flow cytometry after treatment with sensitizing compounds administered at non-cytotoxic concentrations. Results: Sensitizers were able to inducealterations in cell morphology to a more ‘condensed’ one allowing the identification of cells under microscope as a ‘sensitized’ subpopulation. These variations cause similar modifications in ‘scattering’ parameters, making cells easily monitorable by flow cytometry. No changes have been observed in cells treated with non-sensitizers or in untreated cells. Conclusion: This method based on the analysis of forward scatter and side scatter parameters, can be used as an alternative method for identifying sensitization potential of chemical compounds.